Core catcher



July 5, 1938. R, B. GRAINGER 2,122,771

CORE CATGHER Filed Dec. 11, 1957 @www Patented July 5, 1938 CORE CATCHER Reid n. Grainger, Redondo Beach; Calif., assignor to Elliott Core Drilling Company, a corlwration of California.

Application December 11, 1937, Serial No. 179,307

3 Claims. y(Cl. Z55-72) This invention .relates generally to core drills for use in .removing a. core from the hole being drilled in earth formations. More particularly the invention relates to means associated with a core barrel for retaining the core' in the barrel during the removal of the core drilling apparatus and the core from the hole. i

It is the usual practice in connection` with core barrels to use core catching or retaining means at the lower end oi'. thecore barrel in the form of spring ngers or in the form of dogs yieldably held inwardly in the path of 'the core by spring means. The core catching means is mounted at the lower end of the inner core barrel and is designed to breakA off the core and retain it in the core barrel when the apparatus is pulled from the hole.

Where spring lingers-are used'for this purpose they are often ineffective on hard formations-because they fail to dig into the core and break it o s o as to retain the core in the barrel when the core barrel'is lifted. This failure is prinis subsequently raised the fingers, by' reason of their' length and disposition adjacent the inner wall of the barrel. have a low angle of entrance or engagement with the core, and vhence fail to dig into the core, very often permitting the core barrel to be pulled over the core as the spring fingers slide along the sides thereof, thereby resulting in loss of the core. Furthermore, if the core is taken from a. hard formation very often the spring iingerswill break oif and therefore become ineiective for accomplishing the desired purpose.

It is therefore an object of thisinvention to provide means for positively engaging the core to break off the core and hold it in position within the core barrel when the barrel is raised. In accomplishing this object it is a further object oi this invention toprovide dog means for engaging the core which have a high angle of entrance into the core.V Y Y Where shorter dogs are used these are usually yieldably held in position to engage the core and extend inwardly of the core barrel. When the core enters it forces these dogs back against the walls of the inner core barrel against the force oi the springs and often damages the core, especially if the core is taken in soft formation. Usually the springs are ineffective to force the dogs into the core .when the core has been taken from hard formation and the dogs fail to dig into the core and break it off when the core and hold it wlthinthe corevbarrel barrel is raised.

It is therefore an object of this invention to provide a core catching means which `wlll not mar or scariiy the entering core or tend to break it up and in accomplishing this object it is the purpose of this invention to provide dogs which are normally yieldably held in a retracted position out of engagement with the c oi'e. Furthermore, it is an obj ect of this invention to provide means for positively forcing the dogs into engagement .l with the core when the core barrel is raised.

These and other objects will be apparent from the drawing and the following description there- Referring to the drawing, which is for illusltrative purposes only,

Fig. 1 is a fragmentary sectional elevation of the lower end of a core drill showing the inven- -tlon mounted at the lower end of the core barrel.

Fig. 2 is an enlarged fragmentary sectional elevation of the device of Fig. l showing details in the construction. A

Fig. 3 is a sectional elevation on the same plane -as Fig. 2 but showing a core in the barrel engaged by the core catching means of this in.-

vention; and

Fig. 4 is an inverted sectional plan view on line 4 4 of Fig. 3.

Particularly describing the invention, reference numeral I I indicates the lower end of a drill collar to which is threadably attached an ordinary fishtail drill blt I2.

The bit l2 is ofthe ordinary construction and is provided with an annular shoulder I3 which is designed to accommodate the lower end of the core barrel. This .invention has been shown in connection with the so-called wire line core barrels, that is, the type wherein the core barrel I4 is dropped down the hole when it is desired to take a core and it comes to rest in the position shown, the barrel subsequently being raised by means of a Wire line dropped into the. hole and engaging the upper end of the barrel. However, the invention might be used in other types of core drills and is not limited in scope to the particular type of ooring apparatus shown in the drawing.

I4 and which'is I3 of the bit.

adapted to rest upon the shoulder The member IS is provided *.vitl'i auA lateral openings I'I -in which are mounted core catching dogs'j on the pins I6. These plus ae securedin thel bores in any suitable manner. Each of the dogs is provided with alspring 22 which serves tc'yieldably hold the dog against the upper portion ofl the opening I1 in retracted position. j

For the purpose ofV forcing the dogs I8 into engagement with the core. a core engaging mem ber, generallyglindicated by reference numeral 25, is provided. 'This core engaging member fis shown as a core catcher of the ordinary spring finger type, although any member vcapable of yieldably engaging the core mightV be used. Member comprises a cylindrical body member 26 in which are mounted theY upwardly and inwardly extending sprfing fingers 21. The lower end 26 of this member is rounded, as shown.

The core engaging member 25 is sli'dably mounted within the member I6 and the lower rounded end 26 is adapted to engage' the curved surfaces '18 of the dogs I8. v; Y

Referring to Fig. 3 for the operation of the device, it can'be seen that wien a core, generally indicated by 30, enters the cere barrel and it is desired to remove the inner core barrel retainving the core in piace therein, the initial upward movement of the core barrel I4 and its attached coi-:e catching means I5 causes .the

spring fingers 2'I to tend to dig into the clore. These spring fingers 'engage the core suiiiciently to cause relative downward movement of the core engaging member 25, thereby.',forcing the dogs I8 out into engagement with the core as shown in Fig. 3, the Ylower rounded end 26' of the cylindrical bod? member 26 acting as a cam on the rounded surfaces I8' of the dogs I8. The dogs, by reason of their relatively short length, readily dig or bite into the core, entering'ihe sam at a high orl relatively great angle. Further upward movement of the? core barrel causes these dogs to break the corefas indicated in Fig. 3. and retain it within the core barrei when the same is raised in the hole.

It should be apparent from this description that with this' construction soft Acores will not be damaged by reason of the fact that the dogs I8 are held out of engaged position with the entering core. It should also be apparent that a positive means is provided for breaking off and retaining hard cores by reason of the' fact that the springv fingers 2'Iv upon the member 26 suniciently frictionally engage the core when the barrel is raised sc as to cause relative downward movement of themember 26 to the member I6 and thereby serve to-actuate and force the dogs I8 out into engagement with the core, whereby they become eilective to break oi the core and retain it within the core barrel.

I claim as my in'gentlon:

1. For use in combination with a core barrel, core catching' means comprising: a tubular member mounted on the lower end of the core bag-rel; core catching dogs pivotally mounted in sai-:l tubular member; spring means for -ieldably holding said dogs in a retraeted position; acore engaging membr *.slidably; mounted in said tubular member and adapted to engage said dogs. said core engaging member being adapted to force said dogslrj to a core engaging position when said `core barrel is raised with a core therein. V Y

For use in combination with a core barrel, core catching means comprising: a tabular member having lateral openings in its wall mounted on the lower end of the core barrel;

core catching dogs mounted on said'tubular,

member in said openings Vtherein, vsaid dogs extending inwardly'of the inner surface of the tubular member; fispring means yieldably holding said lgo'gs in retracted position; a core engaging member slidably mounted in said tubular member and having a lower cylindrical portion bearing upon said dogs, said core engaging'member being Vadapted to forcesaid d'gs into a core engaging position when said core barrel is raised with a core therein. *Y i 3.V For use in crgambination with a core barrel, core catching means comprising: a tubular member mountedfon the Wlower end of the core barrel, member being provided with lateral openings; pin means extendingvacross each of said openings; a core catching dog mounted on the respective pin means in each of said openings; spring means associated-with'each of said dogs for yieldably holding themy in a retracted position whereby the core engaging ends of said dogs extend inwardly only a limited distance beyond the inner surface of said tubular member; a core engaging member slidably mounted in said tubular member, said core engaging member comprising a lower cylindrical base portion provided withva bevelled lower edge for engaging said dogs and an upper spring portion for engaging a core within said core barrel, said core engaging member being adapted to force said dogs into a core engaging position upon ,upward movement of said core barrel with a core therein.Y 

